A variety of portable electronic devices, such as mobile terminals (e.g., mobile telephones, PDA:s, media players and/or handheld computers), are widely used today. In many of these electronic devices, the keypad can be locked when the portable electronic device is not used. There are many different ways to implement the keypad lock feature. Some mobile terminals use a sequence of two different key-presses to lock the keypad. Some other terminals utilize features like timer lock or keypad lock selection from the menu.
It is known in the prior art that the keypad of a mobile phone (or similar electronic device) can be locked, e.g., by selecting such option from the menu or by pressing a certain key combination. The key-lock function is used to prevent accidental and unintentional key presses, for instance if the device is in a bag, pocket or purse. However, sometimes the user would like to use the device only for one quick operation, e.g. to read a received SMS (Short Message Service) or MMS (Multimedia Messaging Service) message. If the keypad is locked, the user has to unlock the keypad first, subsequently perform the intended operation, and finally remember to lock the keypad again. Another example is when the user wants to use the terminal for a single telephone call, it is then first necessary to unlock the keypad (e.g. by a certain sequence of key-presses), then may be press one or more buttons of the keypad to dial the phone number and after this operation, press two or more keys in a certain sequence to lock the keypad. The above examples of operations may be cumbersome and annoying to some users.
As described earlier, the key-lock function may be used to prevent accidental and unintentional key presses, for instance if the device is placed in a bag/pocket/purse. While the known prior art mobile terminals may provide acceptable locking mechanisms in most cases, there is still a risk that accidental and unintentional key presses occur if the device is in a bag/pocket/purse. For example, if the device is in a bag/pocket/purse it is probable that one or more other objects in the bag/pocket/purse lie against the device. When these objects lie against the device, they may sometimes press the buttons of the keypad of the device by accident. If the device uses a certain key combination for unlocking the key-lock function this certain key combination could in fact be unintentionally or accidentally pressed by the objects lying against the device. There is consequently a risk that the key-lock function would be unintentionally unlocked if objects press the certain key combination by accident. This may lead to the keypad being left unlocked, this in turn potentially leading to accidental phone calls or the like. While the timer lock solves this problem partly, there is still the timeout period when random key-presses can initiate unintentional phone calls or interfere with the operation of the device otherwise, e.g., by entering notes into the calendar or by entering names into the phonebook.